IS it possible to run the panels in series like the way you can with batteries?
Yes, it’s just expensive.
You sure? You can run panels pre-regulated in series but post-regulated in series?
I’d suggest you just have multiple panels each with a smaller battery as safer.
So a little bit of diversity is suggested. I bike camp tour for example and I have a dynohub which has about 0.5A output, sufficient to keep a mobile phone charged whilst riding, usually a 10000mah battery, a 5000mah battery and a solar panel, and a dual port mains charger. Between that lot it covers for example if is sunny outdoors riding I can be charging say the small battery off the hub, the larger battery off solar, if its wet and I find an indoors place I can be charging 2 things at once the mains power like phone+battery or two batteries if the mains power is awkwardly placed.
if you rely on just one technology then you can be caught out, e.g. solar needs sun, what if its not sunny. If you have just 1 battery what if it fails? Would you be better with 2 solar panels charging 2 batteries rather than 2 solar panels in series charging 1 battery? 1 battery can fail. 1 solar panel can fail. etc.